Jupiter’s size just got updated. Astronomers have discovered that this gas giant is not as big as previously thought, thanks to data beamed by NASA‘s Juno spacecraft. A team of scientists from the Weizmann Institute in Israel revealed in a study published in the journal Nature Astronomy that Jupiter is about 8 km (five miles) less wide at the equator and 24 km (15 miles) flatter at the poles.
Turns out Jupiter is slightly smaller and more “squashed” than we orginally thought.
NASA’s Juno mission found the planet is 5 miles narrower at the equator and 15 miles flatter at the poles — key info that will help us study worlds beyond our solar system.
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According to existing data, Jupiter is around 1,42,984 km ( 88,846 miles) across at its equator, and 1,33,708 km (83,082 miles) from pole to pole. Due to its fast rotation [approx. 9 hours 55 minutes], the planet experiences strong centrifugal force which causes it to bulge at the equator and flattens the polar regions – causing it to take an oblate spheroid shape.
The latest measurements were taken more than five decades after observations by NASA’s Voyager and Pioneer missions. But the Juno probe, which is orbiting Jupiter since 2016, collected radio occultation data during its 13 flybys of the planet and made 26 new measurements.
Using radio occultation, Juno peered through the dense and opaque clouds of Jupiter’s atmosphere to understand its internal structure. During a radio occultation experiment, the spacecraft sends signals to NASA’s Deep Space Network from behind Jupiter and as these signals pass through the planet’s atmosphere, they bend and get blocked.
Juno is following a new trajectory since receiving a mission extension in 2021 which takes it behind Jupiter from Earth’s point of view, making the occultation process possible.
“We tracked how the radio signals bend as they pass through Jupiter’s atmosphere, which allowed us to translate this information into detailed maps of Jupiter’s temperature and density, producing the clearest picture yet of the giant planet’s size and shape,” Maria Smirnova, a member of the research team said in a statement.
Prof. Yohai Kaspi of Weizmann’s Earth and Planetary Sciences Department explained that this research would help scientists understand how planets form and evolve because Jupiter was likely the first planet in our solar system. Besides, it also inspires models for studying structures of other giant planets in our solar systems as well as around other stars.
Since Jupiter’s size has been revised, Kaspi believes that the textbooks also need to be updated.
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